Hi Brant,
I’d suggest your concerns are probably valid but I’m not really knowledgeable about these things.

It’ll probably increase your power consumption.

How was the placement communicated to the installer? If you have it in writing, especially if it’s in some form of contract, I’d be pushing to have it installed in the correct position.

Best of luck

If the air con was installed in no 2 position, then cold/hot air would go straight down your stairs. I am not an expert, but I would leave where it is and have a pedestal fan or wall mounted fan installed at position 2, to circulate the airconditioned air into your office area.
This fan may also be useful, when air con is not required, you just need movement of air.

Wall-mounted AC units have a directional outlet on them, so you'll be able to set it to push air across the room. 7.5 metres is a long way for it to travel though, probably won't go that far. The fans are not that powerful.

As for the output size, the rule of thumb for these things is 100W per square metre, so 5kW is about right. With 7kW you should be okay. However your desk is right by a north-facing window so that's where the sun will come in and cook you, unless there's some shading.

The suggestion for a fan is a valid one, and will probably make a big difference. I'm not sure is position 2 would really be a lot better since it's directed at the stair void anyway.

Thermal comfort is always a tricky one since it's very subjective. Ultimately you'll just have to try it and see whether you feel too hot or cold.

But overall I think it won't make too much difference which of the two locations the AC unit is in.

I love that you've allowed us to see the plan of your house. It is fantastic when people give us all the information when they need any help. When it comes to stuff related to your home or anything that can cost you a significant amount of money, I always suggest getting a specialist to help. There are plenty of professionals willing to help somebody with such things to do. When I had an air conditioning installation, I went to see a specialist from the store I bought my system. I have heard there is much stress that gives the possibility of a free consultation if you need help. I wish you good luck, and I hope you'll listen to my advice.